What are endorphins?

Many things can trigger the release of endorphins. Though many triggers are known to exist (which we'll discuss in a moment), the primary triggers are stress and pain. When your hypothalamus detects pain, it issues several orders, one of them being, "Quit telling me it hurts!" (Another one? "Quit touching the hot stove!")

The hypothalamus is the command-and-control center of your endocrine system. It decides when you need to eat, when you should begin puberty and when you need a big dose of endorphins, among many other functions. It keeps tabs on every part of your central nervous system, and hormones are released to other parts of the body when the hypothalamus wants to make an adjustment.

When this part of the brain calls for endorphins, it initiates a chain of messages by chemically prompting the pituitary gland to release its own chemicals that then make their way to glands throughout your body and on down the line until endorphin-containing neurons release them. These endorphins then find their way to the brain's opioid receptors.

Endorphins are produced throughout your body and requested by the hypothalamus, but what else besides stress and pain triggers the release of endorphins?

Exercise -- The "runner's high" really exists, but you'll need to work for it. Heavy weightlifting or intense aerobic activity that includes periods of sprinting or increased exertion will trigger the greatest response.

Ultraviolet light -- This may explain why some users of tanning beds achieve something of a "runner's high," and why others may overuse them at the risk of their health [source: Wake Forest University Baptist Medical Center].